Green tea, coffee drinking promotes longevity

Sipping green tea and coffee may add years to the life expectancy of adults, according to a study from Japan. The former helps brighten the outlook of stroke or myocardial infarction (MI) survivors; the latter produces the same effect but also in people without a history of the said diseases.

“Our observational study suggests that green tea consumption can be beneficial for the secondary prevention of CVD, whereas coffee consumption can also be so for primary prevention,” the investigators said.

They followed 46,213 adults aged 40–79 years at outset for a median of 18.5 years and saw inverse associations between both drinks and all-cause mortality. Green tea intake, for instance, cut the risk by as much as 62 percent in stroke or MI survivors compared with nonconsumption. [Stroke 2021;doi:10.1161/STROKEAHA.120.032273]

The corresponding hazard ratios (HRs) in stroke survivors were 0.38 (95 percent confidence interval 0.20–0.71) for ≥7 cups/day, 0.52 (95 percent CI, 0.31–0.86) for 5 to 6 cups/day, 0.56 (95 percent CI, 0.34–0.92) for 3 to 4 cups/day, 0.65 (95 percent CI, 0.36–1.15) for 1 to 2 cups/day, and 0.73 (95 percent CI, 0.42–1.27) for 1 to 6 cups/week.

Estimates were similar in MI survivors but did not show a signal in individuals without a history of stroke or MI.

Meanwhile, coffee consumption conferred an all-cause mortality benefit in those who had not had stroke or MI, with HRs of 0.86 (95 percent CI, 0.82–0.91) for 1 to 6 cups/week, 0.86 (95 percent CI, 0.80–0.92) for 1 cup/day, and 0.82 (95 percent CI, 0.77–0.89) for ≥2 cups/day.

The corresponding estimates in MI survivors were 0.69 (95 percent CI, 0.53–0.91), 0.78 (95 percent CI, 0.55–1.10), and 0.61 (95 percent CI, 0.41–0.90). Coffee drinking had no favourable effect in stroke survivors.

The study population comprised 478 stroke survivors, 1,214 MI survivors, and 44,521 individuals without a history of either. There were 9,253 cases of all-cause death recorded during follow-up.

“A potential mechanism for the influence of green tea on cardiovascular health can be primarily attributed to the effect of (−)-epigallocatechin3-gallate, which is the most abundant polyphenol in green tea,” the investigators said.

The substance has been shown to have neuroprotective properties in animal studies, reducing ischaemic damage in the acute phase of stroke and promoting neurogenesis after stroke. [Mol Med Rep 2014;9:69-76; Neurochem Res 2015;40:1691-1698; Mol Neurobiol 2017;54:3652-3664]

With respect to caffeinated coffee, intake has been shown to have positive effects on serum cholesterol levels, endothelial function, and inflammation status in diabetic women. Drinking coffee is also linked to higher plasma adiponectin concentrations in women, regardless of diabetes status. [Am J Clin Nutr 2006;84:888-893; Diabetes Care 2008;31:504-507]

Why it does not deliver for stroke survivors is unknown, the investigators said. “One hypothesis is that daily coffee consumption might lead to an increment in blood pressure among stroke survivors. A previous meta-analysis reported that chronic caffeinated coffee consumption was associated with higher systolic and diastolic blood pressure levels, whereas green tea consumption was associated with lower blood pressure levels. [Hypertension 1999;33:647-652; Sci Rep 2014;4:6251]

“More research is needed to confirm the cardio- and neuroprotective effects of green tea and coffee among cardiovascular disease survivors,” they added.